I rarely wear shorts on a plane - not out of any code, but moreso out of the fact that planes can get a bit chilly and I'd rather not get that cold during the flight. Thus, I'll wear khakis or jeans 99% of the time (if it's a short 1 hour flight and I'm going to a warm destination, then I'll wear the shorts but that's about it).

As for exact attire, depends on my need for my destination. If it's a full leisure trip, I'll wear jeans and either a t-shirt or a golf shirt (untucked). If I'm going out to a decent dinner upon arrival, I'll probably wear khakis and a golf shirt (tucked - that's Catholic school upbringings there with wearing khakis = shirt tucked in) or, if it's colder, a button down. In the few times I've had to do business upon landing (or coming from a business meeting), I'll just wear the suit.